Production of white pulp.



UNETED STATES PATENT @FFTQE.

ALBERT GAGEDOIS, OF DON, NEAR ANNCEULLIN, FRANCE.

PRQDUCTION OF WHITE PULP.

To all ur/umt it may concern:

Be it known that I, ALBERT GAGEDOIS, a citizen of the Frenchllepublic, residing at 1 Don, by Annceullin, Nord, France, have invented certain new and useful Improvcmen ts in the Production of l/Vhite Pulps, of which the following is a specification.

Hitherto, as far as known to me, the production of pure white pulp for use in papermaking has only been possible by using raw material which was white at starting and not much soiled.

The process which forms the object of this invention enables .pulps of pure and brilliant whiteness to be obtained by employing wood, hemp, jute, phormium, aloes, and other similar vegetable products in the natural state, white or colored rags, old ropes, and other waste material, even if colored, as also the white waste material from spinning-works, hitherto exclusively employed for manufacturing white pulps. In order to efifect this bleaching of materials, hitherto regarded as not capable of being utilized inthe manufacture of white pulps for use in making white paper, the natural vegetable products are subjected to the following operations preparatory to the bleaching: First, one or more lye-washings with lime or with soda, followed by a thorough washing, in the first place with acidulated water when lime-lye has been used, and then with fresh clean Water, so as to obtain a neutral pulp free from reagents; secondly, chlorination, in the case of woodpulps. This chlorination is followed by the necessary washings with pure water in order to obtain. a neutral. pulp. The bleaching is then efiected, the materials which have been treated with lye or with lye and chlorin being beaten for four to six hours in a bath constituted as follows: In the necessary quantity of clean cold water for well moistening the pulp to be converted mto paper two to three kilograms oi alkalin peroXid per hundred kilograms of material are dissolved, according to the quality of the material and the extent to which it is prepared for bleaching. To this solution ten to thirty kilograms of neutral alkalin silicates of 5 Specification of Letters Patent. Application filed February 2, 1906. Serial No. 299,154.

,tard, as above explained.

Patented March 26, 1907.

grams of material.

The function of the alkalin silicate is to retard the decomposition of the peroxid and allow the liberated oxygen to act gradually on the pulp to be bleached. This it does, in

part, by obstructing the decomposition by heat and in part by thickening the mass, and thus obstructing the free escape of the nascent oxygen and compelling its contact with all of the particles of the pulp.

During the heating, which is continuous, the temperature is gradually raised to about 80 centigrade. This increase of the temperature is only intended to effect the decomposition of the peroxid in the baths which does not contain any reagent, so that the oxidation is carried on gradually throughout the material without injury to the pulp under treatment. The alkalin silicate employed will be neutral, and it will not react on or ail'ect the alkalin peroxid. The heat alone decomposes the peroxid, and the alkalin silicate merely acts mechanically to re- The pulp is then washed with clean cold Water and subjected to the following operations: first, soaping in a tub or trough provided with a stirrer; secondly, chlorination ,followed by the necessary washings for eliminating all traces of chlorin.

If the materials employed in the manufacture of the white paper are wastecoloredfabrics, the lye-washings are preceded by a decoloring operation consisting in beating the said fabrics in a solution of nitric acid of 2 Baum containing 'Iii'teen to twenty per cent. of the said acid. This decoloring operation is followed by a washing with clean cold water.

What I claim, and desire to secure by Letters Patent, is-

1. The herein-described process of treating a neutral, cleansed, vegetable pulp for paper and the like, which consists in mixing the pulp with alkalin peroxid, and neutral alkalin silicate as a retarder, the pulp, peroxid and silicate being in about the proportions specified, then heating the mixture gradually,

[ Baum are added for each one hundred kilofor decomposing the peroxid,' up to about a mixture of neutral alkalin silicate and an 10. 80 centigrade, and finally soaping and chloalkalin peroxid, and finally soaping and chlorinating the pulp so treated. rinating thematerial treated,

22. The herein-describedproeess of treating I In testimony whereof I have afllxed my' vegetable pulps for )aper and the like, which signature in presence of two witnesses. consists in first was ing the pulp thoroughly ALBERT GAGEDOIS. with lye, then chlorinating, then Washing it Witnesses: to rod'uce a neutral pulp, then heating the EIs. HOBRAUS,

pu p gradually up to about 80 centig'rade in i TH. PALLE T. 

